This invention relates to the recovery of energy from geothermal brines and other hot water sources, and is particularly concerned with a process and system of the aforementioned type, employing direct contact heat exchange between the hot brine or hot water feed, and a working fluid under certain pressure and temperature conditions, wherein the heated working fluid is expanded to produce work, and the expanded and discharge working fluid is recycled to the heat transfer column, and further providing for working fluid recovery under conditions to afford an economic balance between energy recovery and working fluid loss.
In prior art processes and systems for recovery of energy from geothermal brines and other hot water sources, employing heat exchange between the hot brine or hot water, and a working fluid, there has been no recognition heretofore of the problem of obtaining a heat balance in the heat transfer column with close temperature differentials or .DELTA.t's between brine or water and working fluid, to obtain maximum efficiency. The prior art also has failed to recognize the problem of working fluid loss in uncondensible gases which come into the system particularly with the hot brine or hot water and which must be vented. Further, the prior art has failed to provide for the problem of working fluid loss in exit brine or hot water from the heat transfer column, and recycle of such recovered working fluid to the heat transfer column.
It is accordingly a chief object of the invention to provide a process and system for recovery of energy from geothermal brines and hot water sources by operation of a heat transfer column preferably providing direct heat transfer between the hot brine or hot water, and a working fluid, under conditions of operation particularly with respect to pressure in the heat transfer column and temperature of the hot brine or hot water feed, in relation to the critical pressure and temperature of the working fluid, to allow maximum energy recovery for any individual working fluid. A further object is the provision in the procedure and system, for removal of working fluid from the exit brine or water from the column and recovery of such working fluid. A still further object is the control of the working fluid concentration in the uncondensible vent gas from the system to obtain an economic balance between energy recovery from the process and system, and working fluid loss in the uncondensible vent gas.